Scoping out the tide of birds

Spring migration highlights avian navigational skills

Birders aim their binoculars at high branches to watch warblers during a walk at Willowbrook Wildlife Center in Glen Ellyn. (Chuck Berman, Chicago Tribune)

The first thing Ron Skleney did was tamp down our expectations.

Yes, birds were on the wing, migrating our way in force. Skleney, naturalist at the Willowbrook Wildlife Center in Glen Ellyn, showed our bird walk group the radar map that proved it. Made with readings taken at 2 a.m., it showed the lower half of the eastern/central U.S. covered with blue dots representing concentrations of birds, like a northbound blue tide.

But our late spring meant that the trees here were only starting to leaf out. That meant fewer insects, which feed on the leaves. And that would presumably mean fewer migrating birds, which feed on insects.

"I wouldn't expect a whole lot, warbler-wise," Skleney told the binocular-toting gathering, which was large enough that he divided us into two groups.

But minutes after our group set out, people were calling out so many warbler sightings that it was hard — in my case impossible — to keep up.

"A Nashville!"

"Yellow warbler!"

"I've got a black-throated green warbler."

"Blackburnian!"

This last, from sharp-eyed 17-year-old Graham Deese — he and his younger brother are volunteers at Willowbrook who help lead bird walks — got my beginner's heart racing. I had seen pictures of the orange- and black-streaked Blackburnian — like a Hot Wheels car painted with flames, Skleney put it — and wanted to see the real thing.

However, it was a devilishly overcast morning, dulling the appearance of brightly-colored birds. Adding the fact that warblers are small and move fast, even the veteran birders were struggling.

"Oh, crap," sighed Joan Campbell, who leads bird walks at Lyman Woods, as the Blackburnian flitted off before she could get her binoculars on it.

I saw only a fraction of the birds others saw, even with such excellent directions as these from Deese: "The second peeling-bark tree, at the branch that comes in level with the main trunk of the first peeling-bark tree, then look up in the canopy."

But I finally saw that Blackburnian.

"Everyone got the Blackburnian?" Skleney called out. "OK, we can go home now."

We didn't, of course. Over the course of an hour and a half, we — and by "we," I mean "they" — saw 52 species, combining both groups' totals, including eight birds seen for the first time this season.

"This is the best day so far this year, no doubt about it," Skleney said happily. "I'm really kind of amazed."

"Pine warbler," Deese called out.

"Oh, crap," Campbell said.

Challenges aside, spring migration is considered primo birding time.

"If you're a birder, it's like the Super Bowl, the World Series and the Stanley Cup playoffs all rolled into one," Skleney said.

Or, as internationally known birder and field guide author Kenn Kaufman thinks of it, a cross between science and magic — the title of the talk he will give on spring migration on May 18 at Ryerson Woods.

"For me it's really hard to separate the scientific and the magical," Kaufman, author of the classic birding memoir "Kingbird Highway," said from his home in Ohio. "The more straight facts we know about it, the more amazing it becomes."

"It's literally billions of individual birds. They're spread out across the entire continent," he said. "Most are migrating at night. It's fascinating to realize up there on a night when the winds are right — when you have a night in spring where there's a clear sky and winds are out of the south — there may be many millions of birds coming north at the same time."

And lucky us, to live on the Lake Michigan shoreline where they often stop to rest.

As for the science, Kaufman said, it lies in birds' prodigious navigational abilities.

"They use the stars for direction," he said. "And a lot of birds can detect the earth's magnetic field.

"Some kinds of birds are extremely sensitive to extremely low-pitched sound. They may be able to pick up sounds of waves crashing on a beach hundreds of miles away. ... If they're flying in daytime and it's cloudy, they can detect the angle of the light coming through the clouds, so even in a heavy overcast they can tell where the sun is.

"There are probably other abilities we don't know about yet," he said. "You can have a bird literally migrating from Alaska to Brazil in the fall, then from Brazil back to Alaska — and end up in the same tree they came from. It's amazing pinpoint accuracy."

And it's ours to see, right now.

There are spring bird walks like this one throughout the area, and beginners are not only welcome but often the source of walk leaders' greatest satisfaction.